Synthesis and antimicrobial activity of some spiroheterocyclic compounds containing indole nucleus

Abstract

Indole-3-carboxaldehydes (1) were prepared by Vilsmeier-Haack formylation of substituted indoles. These aldehydes (1) on cyclodehydration with acetone or ethyl methyl ketone in presence of anhyd ammonium acetate afforded 2,6-bis-(2?,5?-substituted indole-3?-yl) piperidin-4-ones (2). Compounds (2) on reaction with thiosemicarbazide in methanol containing catalytic amount of concentrated HCI yielded 2,6-bis-2-(2?,5?- substituted indole-3-yl) piperidin-4-one thiosemicarbazones (3) which on oxidative cyclization with acetic anhydride afforded N-acetyl-[2,6-bis- (2?,5?-substituted indol-3?-yl) piperidin-4-yl]-5-spiro-4- acetyl-2-(acetamido)-?2-1,3,4-thiadiazolines (4). The compounds were characterized by their analytical and spectral data and screened for their antimicrobial activity.